Sliding Closure for Metallurgical Vessels

ABSTRACT

Disclosed is a sliding closure for metallurgical vessels, comprising at least two fireproof closing parts that can be braced against each other by means of spring elements ( 5 ). At least one measuring apparatus ( 10 ) is provided for measuring the distance of the housing parts or the closing parts from each other regarding the displacement thereof transversal to the sliding areas while at least one temperature gauge is provided which is connected to an evaluation unit ( 20 ). The apparatus ( 10 ) for measuring the position of the closing parts encompasses exploring coils ( 12, 13 ) that are mounted next to each other and a core ( 15 ) located in a central opening ( 11   a ) in said coils, each of which is arranged in one of the two housing parts and which jointly form a differential throttle. The core ( 15 ) can be adjusted perpendicular to the sliding areas when the distance between the two housing parts changes, whereby a tension can be generated which can be transmitted to the evaluation unit ( 20 ). Said measurement makes it possible to improve the operational safety of such a sliding closure.

The invention concerns a sliding closure for metallurgical vesselsaccording to the preamble of claim 1.

A sliding closure of this type is disclosed in WO 03/080274. Closingparts for sliding closures of this type are obviously exposed to heavywear and therefore have to be replaced frequently. For economic reasons,however, every effort is made to use these closing plates for as long aspossible. In order nevertheless to guarantee a high level of operationalsafety and detect any nascent operational faults at an early stage, itis known from WO 03/080274 to equip the sliding closure with at leastone measuring apparatus with which the position of the closing plates,which are displaceable with respect to each other on sliding areas, canbe measured and evaluated in terms of their change transverse to thesliding areas. By measuring the distance between the housing parts whichaccommodate the respective closing plate, any changes in the position ofthe closing plates, such as e.g. those which arise when steel meltpenetrates between the closing plates and there forms a thin sheet, arediagnosed at an early stage. This can prevent steel melt from flowingout uncontrolled between the closing plates.

The problem with measuring the position of the closing plates lies inthe large temperature range in which the distance and/or change indistance has to be measured. The temperature differential between thestart temperature (e.g. 24° C.) and the end temperature (e.g. 345° C.)is considerable (here it is 321° C.). This means that the distance incold and in hot condition may vary by several millimetres.

The present invention is based on the problem of creating a slidingclosure of the type mentioned above which has a high level ofoperational safety, and in which, at little expense, unacceptabledeviations in the position of the closing plates can be determined withsufficient accuracy while taking account of distance changes due totemperature.

This problem is solved according to the invention by a sliding closurewith the features of claim 1.

Further preferred embodiments of the sliding closures according to theinvention form the subject matter of the dependent claims.

The sliding closure according to the invention is fitted with ameasuring apparatus which comprises two exploring coils attached side byside on a coil body built into the two housing parts, and a core placedin a central opening of the coil body, longitudinally displaceable inthe axial direction of the coil body, which together form a differentialthrottle. When the distance between the two housing parts changestransverse to the sliding areas of the closing plates, the core isdisplaced from a central position with respect to the exploring coilswhereby a voltage can be generated which can be transmitted to anevaluation unit. A good reproducibility of the measurements of distancechanges at various temperatures was achieved with the measurementdevice. Temperature drift is small due to the compensation of the twoexploring coils with respect to their change in resistance, whichenables a formula-based temperature compensation to be realised. Thisallows distance changes in a measurement range of 8 mm to be determinedto an accuracy of less than 0.1 mm. The sliding closure according to theinvention thus has a high level of operational safety. Faults and inparticular breakouts, in which often the entire sliding closuremechanism and possibly also parts of the continuous casting plant can bedestroyed, can be largely prevented. Assembly faults on the slidingclosure can also be detected and resultant breakouts can also beprevented.

The invention will next be explained in more detail with the aid of thedrawings, which show:

FIG. 1 cross-section of a part of a sliding closure according to theinvention with a built-in measuring apparatus;

FIG. 2 schematic view of the basic parts of the measuring apparatusaccording to FIG. 1; and

FIG. 3 a circuit diagram of the measuring apparatus for measuring andanalysing the position of the closing plates.

FIG. 1 shows part of a sliding closure, comprising as closing parts atleast two refractory closing parts that can be braced against each otherin a way known per se, each disposed in a housing part and displaceableon sliding areas with respect to each other. For example this may be asliding closure corresponding to that in WO 03/080274, FIG. 2, and whichhas a fixed, upper housing part attached to a vessel with the oneclosing plate and a lower housing part movable with respect thereto andprovided with the other closing plate, where the movable housing partand with it the other closing plate is displaceable by means of a drivebody into a closed or open position, as the case may be. The closingplates themselves are not shown in FIG. 1, and only the one housing part1 of the housing parts is shown, the embodiment shown being the fixedupper housing part.

A guidance unit 2 is built into the fixed housing part 1—similarly tothe sliding closure according to WO 03/080274, FIG. 2—which has a guidepin 4 accommodated in a housing 3, on the lower end 4 a of which atleast one guide element, e.g. a guide roller, preferably two parallelguide rollers, not however shown in FIG. 1, is or are attached. A springelement 5 is arranged at the perimeter of the guide pin 4, which issupported on one side on a lower shoulder area 3 a of the housing 3 andon the other side on the guide pin 4 and presses the guide pin 4 upwardsand with it the guide roller from below onto a guideway of the movablehousing part. There is also a bearing ring 17 held in the upper part ofthe housing 3, which serves as a stop for the coil body 11 and for theguide pin 4.

There are of course several such guide units 2 with spring elements 5built into the fixed housing part 1, via which the lower housing part ispushed upwards and the closing plates are tensioned against each other.

In accordance with FIG. 1, a measuring apparatus 10 for measuring theposition of the closing plates with respect to its change transverse tothe sliding areas is assigned to one of these guide units 2. The basicparts of this measuring apparatus 10 are also shown in FIG. 2, and FIG.3 shows a corresponding circuit diagram. The measuring apparatus 10comprises two exploring coils 12, 13 attached to a coil body 11 (FIG. 2)and a magnetic core 15 located in a central opening 11 a of the coilbody 11, longitudinally movable via a non-magnetic connecting rod 16 inthe axial direction of the coil body, which jointly form a differentialthrottle. The voltage changes caused by the movements of the magneticcore 15 from a central position as shown in FIG. 2 (in the middle,between the two exploring coils 12, 13) can be measured in a bridgecircuit. The differential throttle can be operated with an ordinarycommercial carrier frequency amplifier 19 with integrated phasedemodulator 19 (FIG. 3).

According to the invention, the core 15 is assigned to the guide unit 2or its spring-loaded guide pin 4 respectively, and is in fact built intothe guide pin 4, with the tension rod 16 on its front face, at its upperend. The coil body 11 with the exploring coils 12, 13 (FIG. 2) is builtinto the fixed housing part 1 above the guide unit 2, in such a way thatthe tension rod 16 with the core 15 protrudes into the central openingIIa.

Changes in the distance of the two sliding closure-housing parts and thetwo closing plates respectively transverse to their sliding surface canbe measured using the measuring apparatus 10. If, for example, steelmelt penetrates between the closing plates, a thin sheet may form therewhich forces the closing plates apart. As the result of this, the lowerhousing part is forced downwards, against the force of the springelements 5, and also the guide pin 4 supporting the guide rollers isforced downwards via its guideways. Also, the guide pin 4 fitted withthe tension rod 16 and the core 15 is moved downwards in the housing 2against the force of the spring element 5 and the core 15 is shifted outof its central position, at which the measuring voltage is zero, thuscreating a voltage which is transmitted via the phase demodulator 19 tothe evaluation unit 20. This voltage is compared with the voltage of areference coil 21 measured at room temperature (FIG. 3), which is alsotransmitted to the evaluation unit 20.

There is also a temperature measurement apparatus attached to theevaluation unit 20, which includes the temperature sensor arranged nearthe closing plates, but not visible in the drawing.

As already mentioned, the measured distance between the two slidingclosure housing parts and between the two closing plates istemperature-related. In order to compensate computationally for thedeviations due to temperature, a measuring apparatus had to be foundwith which reproducible measurement results could be achieved. Goodreproducibility of measurements was achieved using the measuringapparatus 10 acting as a differential throttle; due to the compensationof the two exploring coils 12, 13 (with respect to their change inresistance) temperature drift is substantially less than with othermeasurement systems which were also tested (e.g. solenoid plungersystem). Due to this good reproducibility, it is possible to realise aformula-based temperature compensation. As a result, distance changes ina measurement range of 8 mm can be determined to an accuracy of lessthan 0.1 mm.

The sliding closure according to the invention, equipped with themeasuring apparatus 10 acting as differential throttle, has a high levelof operational safety. Faults and in particular breakouts, in whichoften the entire sliding closure mechanism and possibly also parts ofthe continuous casting plant can be destroyed, can be largely prevented.Assembly faults on the sliding closure can also be detected andresultant breakouts can also be prevented.

It is of course also possible to build the coil body 11 into thespring-loaded guide pin 4 and to assign the core 15 to the fixed housingpart 1.

For economic reasons, only one of the guide units 2 is assigned to themeasuring apparatus 10. However, it would certainly also be possible toprovide such measuring apparatuses at several points.

The measuring apparatus 10 for measuring the distance and the distancechanges respectively between the two sliding closure-housing parts couldalso be attached elsewhere on the sliding closure than in one of theguide units 2. For example, it could—similarly to the sliding closureaccording to WO 03/080274, FIG. 2—be arranged laterally on the housingparts, in which case the displaceability of the one housing part wouldhave to be taken into account.

A casting pipe changer could also be used as sliding closure, in whichrefractory casting pipes could be swapped as closing parts. Instead ofclosing plates, closing sleeves or similar could also be used.

1. Sliding closure for metallurgical vessels, having at least tworefractory closing parts that can be tensioned against each other, whichare each displaceably arranged with respect to each other in a housingpart on sliding areas, while spring elements (5) are contained in atleast one of the housing parts to tension the closing parts, while atleast one measuring apparatus (10) to measure the distance of thehousing parts and/or the closing parts with respect to each other interms of their change transverse to the sliding areas and at least onetemperature-measuring apparatus are provided, said measuring apparatuses(10) being attached to an evaluation unit (20), characterised in thatthe measuring apparatus (10) for measuring the closing parts positioncomprises exploring coils (12, 13) mounted next to each other and a core(15) located in a central opening (11 a) in said coils, each of which isarranged in one of the two housing parts and which jointly form adifferential throttle. The core (15) can be adjusted transverse to thesliding areas when the distance between the two housing parts changes,whereby a voltage can be generated which can be transmitted to theevaluation unit (20).
 2. Sliding closure according to claim 1,characterised in that two exploring coils (12, 13) mounted next to eachother on a coil body (11) built into one of the two housing parts andthe core (15) which is longitudinally displaceable in the axialdirection of the coil body (11) are provided, while the core (15) isdisplaceable from a central position with respect to the exploring coils(12, 13) if there is any change in the distance of the two housing partstransverse to the sliding areas.
 3. Sliding closure according to claim2, characterised in that the measuring apparatus (10) for measuring theposition of the closing parts is assigned to a guide unit (2) built intothe fixed housing part (1), said guide unit having a spring-loaded guidepin (4), which carries at least one of the guide elements which can bepressed onto a guideway of the displaceable housing parts, while one ofthe two measuring apparatus parts (coil body with exploring coils/core)which are movable relative to each other is built into the guide pin(4).
 4. Sliding closure according to claim 3, characterised in that theguide pin (4) carries the guide element or guide elements on its lowerend and at its perimeter is surrounded by one of the spring elements (5)which can be pressed from below onto the guide elements on the guidewaysof the displaceable housing parts, while the magnetic core (15) is builtinto the front face of the upper end of the guide pin (4) by means of anon-magnetic tension rod (16) and is positioned in the fixed coil body(11) located above this.
 5. Sliding closure according to claim 1,characterised in that one of the two housing parts is provided withguideways parallel to the sliding areas and the other with guideelements which can be pressed onto the guideways.